Inorganic perovskite engineering through incorporation of a carboxylic acid containing ligand for performance enhancement in perovskite light-emitting diodes

Abstract

Inorganic cesium lead halide perovskites (such as CsPbBr₃) are emerging as one kind of promising optoelectronic material with good stability, narrow color spectrum and facile bandgap tunability. However, the morphology issue of CsPbBr₃ film limits its applications in perovskite light-emitting diodes (PeLEDs). Here, we present an effective strategy of perovskite structure engineering by incorporating a long chain cation ligand (HOOC-PMA-Br) into CsPbBr₃, aiming to optimize perovskite morphology and thereby improve device performance. It is found that the HOOC-PMA-Br ligand plays a key role in controlling the dimension and crystal growth of perovskites, attributed to the formation of hydrogen bond networks induced by the carboxylic acid unit. With an optimized doping ratio of HOOC-PMA-Br, (HOOC-PMA)₂CsPb₂Br₇ perovskite not only maintains a 3D structure but also presents excellent morphology with a uniform distribution of smaller grain size, smoother surface and better coverage like that of a quasi-2D structure, along with a much higher photoluminescence quantum yield than that of pure CsPbBr₃. Significantly, (HOOC-PMA)₂CsPb₂Br₇ endows PeLEDs with remarkably higher luminance and efficiencies than that of CsPbBr₃ based devices.